Effectiveness of Various Artificial Larval Diets for Rearing Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) in the Laboratory in Fiji

Laboratory colonies of Bactrocera passiflorae (Froggatt) and B. xanthodes (Broun) were established at Koronivia Research Station, Fiji in 1991. Laboratory rearing of the two economically important species was a prerequisite to studies conducted on protein bait spray and quarantine treatment development. To increase the production of laboratory reared fruit flies for this research and also to have a substitute larval diet available, replicated comparisons of the effectiveness of larval diets were carried out using B. passiflorae and B. xanthodes. The diets compared were pawpaw/bagasse, dehydrated carrot and diets used for culturing Mediterranean fruit fly (Ceratitis capitata Wiedemann), Oriental fruit fly (B. dorsalis Hendel), melon fly (B. cucurbitae Coquillett) and B. latifrons (Hendel), pawpaw diet and breadfruit diet. B. passiflorae and B. xanthodes eggs seeded onto the various diets were allowed to develop into larvae, pupae and adults. The percentage egg hatch, number of pupae recovered, percentage pupal mortality, weight of 100 pupae, number of adults and percentage eclosion were used to determine the effectiveness of the diets. Results showed that pawpaw/bagasse and dehydrated carrot diets performed favorably for both species. The pawpaw diet currently used as standard larval diets for both species is the most readily available and easiest to use. Breadfruit diet was tested on B. xanthodes only and showed that it was a suitable substitute for the pawpaw-based diets. Other larval diets, cassava/pawpaw and banana diets, that have been developed and used in the South Pacific areas are also discussed in this paper. When pawpaw or breadfruit are not available, dehydrated carrot diet may be substituted for fruit-based larval diets.

Artificial neural networks in modelling osmotic dehydration of foods

Artificial neural network (ANN) models for water loss (WL) and solid gain (SG) were evaluated as potential alternative to multiple linear regression (MLR) for osmotic dehydration of apple, banana and potato. The radial basis function (RBF) network with a Gaussian function was used in this study. The RBF employed the orthogonal least square learning method. When predictions of experimental data from MLR and ANN were compared, an agreement was found for ANN models than MLR models for SG than WL. The regression coefficient for determination (R2) for SG in MLR models was 0.31, and for ANN was 0.91. The R2 in MLR for WL was 0.89, whereas ANN was 0.84.Osmotic dehydration experiments found that the amount of WL and SG occurred in the following descending order: Golden Delicious apple > Cox apple > potato > banana. The effect of temperature and concentration of osmotic solution on WL and SG of the plant materials followed a descending order as: 55 > 40 > 32.2C and 70 > 60 > 50 > 40%, respectively.

Nuclear magnetic resonance water relaxation time changes in bananas during ripening: a new mechanism

BACKGROUND: Nuclear magnetic resonance studies of banana fragments during ripening show an increase on the water transverse relaxation time (T(2)) and a decrease in water self-diffusion coefficient (D). As T(2) and D are normally directly correlated, we studied these two properties in intact bananas during ripening, in an attempt to rule out the effect of injury on the apparent discrepancies in the behavior of T(2) and D. RESULTS: The results show that injury in bananas causes a decrease in T(2) of the water in vacuoles (T(2vac)). They also show that T(2vac) increased and D decreased during ripening, ruling out the injury effect. To explain the apparent discrepancies, we propose a new hypothesis for the increase in T(2) values, based on the reduction of Fe(3+) ions to Fe(2+) by galacturonic acid, produced by the hydrolysis of pectin and a decrease in internal oxygen concentration during ripening. CONCLUSION: As injury alters T(2) values it is necessary to use intact bananas to study relaxation times during ripening. The novel interpretation for the increase in T(2vac) based on reduction of Fe(+3) and O(2) concentration is an alternative mechanism to that based on the hydrolysis of starch in amyloplasts. (C) 2010 Society of Chemical Industry

Amadurecimento da banana-prata climatizada em diferentes dias após a colheita

O amadurecimento induzido por climatização em bananas, é um procedimento que tem sido largamente utilizado. Ele proporciona uma maturação uniforme, já que a fruta apresenta maturação desuniforme em vista da formação dos frutos em pencas com diferentes idades. No entanto, não há para todas as cultivares de banana, estudos específicos em relação ao tempo entre a colheita e a climatização que possa afetar a qualidade dos frutos. Desta forma, com o presente trabalho objetivou-se avaliar mediante as características físicas, químicas e fisiológicas a qualidade da banana - prata climatizada em diferentes dias entre a colheita e a climatização. Foram testados três diferentes dias de climatização sendo 1, 2 e 3 dias após a colheita. Ao final da climatização, os frutos foram armazenados em temperatura ambiente por um período de 5 dias. As análises realizadas foram: perda de massa, coloração da casca, respiração, firmeza, pH, sólidos solúveis, acidez titulável e amido. Frutas climatizadas 1 dia após a colheita apresentaram-se, no 1º dia de armazenamento, com menor perda de massa, mais verdes, com maior liberação de CO2, mais firmes, com menores teores de sólidos solúveis e maior porcentagem de amido, quando comparados àqueles climatizados aos 2 e 3 dias após a colheita. Essa diferença foi reduzida com o decorrer do armazenamento praticamente se igualando os tratamentos ao final do armazenamento.

Controle do amadurecimento de banana 'Prata-Anã' armazenada sob refrigeração e atmosfera modificada passiva com o uso do 1-metilciclopropeno

O 1- Metilciclopropeno (1-MCP) é um produto inovador que inibe a ação do etileno em vegetais, retardando o início do amadurecimento de pomáceas, frutas de caroço e frutas tropicais. Com este trabalho objetivou-se avaliar a eficiência de diferentes concentrações do 1-MCP no controle do amadurecimento de bananas 'Prata-Anã' produzidas no Norte de Minas Gerais, armazenadas a 12°C e 95% de UR sob atmosfera modificada passiva. Os cachos foram colhidos no grau 1 de coloração da casca, que corresponde ao estádio verde de maturação. Foram utilizadas somente as segundas pencas dos cachos selecionados e estas foram separadas em buquês de 4 frutos. Cada parcela constou de 4 repetições e cada repetição 1 buquê. As concentrações do 1-MCP aplicadas foram: 0, 30, 60 e 90 ppb. Os frutos foram acondicionados em bandejas de isopor e embalados em filme de PVC de 15 micras, armazenados a 12°C e 95% de UR, sendo avaliados aos 10, 15, 20, e 25 dias. As avaliações realizadas constaram de diâmetro, grau de coloração da casca, firmeza, sólidos solúveis, acidez titulável e pH. A aplicação do 1-MCP foi eficaz em retardar o amadurecimento de bananas 'Prata-Anã' cultivadas na região Norte de Minas Gerais. As concentrações de 30, 60 e 90 ppb não apresentaram efeito diferenciado quanto às características avaliadas, podendo ser utilizada a concentração de 30 ppb, com economia do produto, obtendo-se os mesmos benefícios das concentrações de 60 e 90 ppb.

Qualidade e conservação de banana nanica irradiada, climatizada e refrigerada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

The effect of power-ultrasound on the pretreatment of acidified aqueous solutions of banana flower-stalk: Structural, chemical and statistical analysis

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Mathematical modeling of drying process of unripe banana slices

Unripe banana flour (UBF) production employs bananas not submitted to maturation process, is an interesting alternative to minimize the fruit loss reduction related to inappropriate handling or fast ripening. The UBF is considered as a functional ingredient improving glycemic and plasma insulin levels in blood, have also shown efficacy on the control of satiety, insulin resistance. The aim of this work was to study the drying process of unripe banana slabs (Musa cavendishii, Nanicão) developing a transient drying model through mathematical modeling with simultaneous moisture and heat transfer. The raw material characterization was performed and afterwards the drying process was conducted at 40 ºC, 50 ºC e 60 ºC, the product temperature was recorded using thermocouples, the air velocity inside the chamber was 4 m·s-1. With the experimental data was possible to validate the diffusion model based on the Fick\'s second law and Fourier. For this purpose, the sorption isotherms were measured and fitted to the GAB model estimating the equilibrium moisture content (Xe), 1.76 [g H2O/100g d.b.] at 60 ºC and 10 % of relative humidity (RH), the thermophysical properties (k, Cp, ?) were also measured to be used in the model. Five cases were contemplated: i) Constant thermophysical properties; ii) Variable properties; iii) Mass (hm), heat transfer (h) coefficient and effective diffusivity (De) estimation 134 W·m-2·K-1, 4.91x10-5 m-2·s-1 and 3.278?10-10 m·s-2 at 60 ºC, respectively; iv) Variable De, it presented a third order polynomial behavior as function of moisture content; v) The shrinkage had an effect on the mathematical model, especially in the 3 first hours of process, the thickness experienced a contraction of about (30.34 ± 1.29) % out of the initial thickness, finding two decreasing drying rate periods (DDR I and DDR II), 3.28x10-10 m·s-2 and 1.77x10-10 m·s-2, respectively. COMSOL Multiphysics simulations were possible to perform through the heat and mass transfer coefficient estimated by the mathematical modeling.

Effects of chilling temperatures on ethylene binding by banana fruit

Banana fruit are highly susceptible to chilling injury during low temperature storage. Experiments were conducted to compare ethylene binding during storage at chilling (3 and 8 degreesC) versus optimum (13 degreesC) temperatures. The skins of fruit stored at 3 and 8 degreesC gradually darkened as storage duration increased. This chilling effect was reflected in increasing membrane permeability as shown by increased relative electrolyte leakage from skin tissue. In contrast, banana fruit stored for 8 days at 13 degreesC showed no chilling injury symptoms. Exposure of banana fruit to the ethylene binding inhibitor 1-methylcyclopropene (1 mul l(-1) 1-MCP) prevented ripening. However, this treatment also enhanced the chilling injury accelerated the occurrence of chilling injury-associated increased membrane permeability. C-14-ethylene release assay showed that ethylene binding by banana fruit stored at low temperature decreased with reduced storage temperature and/or prolonged storage time. Fruit exposed to 1-MCP for 12 h and then stored at 3 or 8 degreesC exhibited lower ethylene binding than those stored at 13 degreesC. Thus, chilling injury of banana fruit stored at low temperature is associated with a decrease in ethylene binding. The ability of tissue to respond to ethylene is evidently reduced, thereby resulting in failure to ripen.

Manipulating avocado fruit ripening with 1-methylcyclopropene

Previous investigations with 1-methylcyclopropene (1-MCP) on avocado (Persea americana Mill.) fruit have focussed mainly on improving storage life by reducing the severity of disorders causing discolouration of the flesh. Development of 1-MCP and ethylene treatments, which also help control the time to reach the eating ripe stage, may confer additional practical benefits. In this context, the current study investigated the potential of 1-MCP to accurately manipulate ripening of non-stored 'Hass' avocado fruit by treatment before or after ethylene and at different times during ripening. To investigate this, 500 nL L-1 1-MCP was applied within 1 day after harvest, followed by ethylene 0-14 days after 1-MCP. In addition, fruit were treated with ethylene, then 1-MCP 0-8 days after ethylene. Treatment of fruit with 500 nL L-1 1-MCP for 18 h at 20 degreesC provided the maximum effect by increasing the days from harvest to ripe (DTR) from 8 (with no 1-MCP) to 20. Fruit treated with 500 nL L-1 1-MCP for 18 h at 20 degreesC remained insensitive to 100 muL L-1 ethylene applied between 0 and 14 days after 1-MCP for 24 h at 20 degreesC. Ripening of fruit exposed to 100 muL L-1 ethylene for 24 h at 20 degreesC could be delayed by up to 3.3 days by applying 500 nL L-1 1-MCP for 18 h at 20 degreesC up to 2 days after ethylene treatment. However, once the fruit started to soften (sprung) there was little effect of 1-MCP on DTR, compared with no 1-MCP. 1-MCP treatment was associated with increased severity of body rots (caused mainly by Colletotrichum spp.) and stem-end rots (caused mainly by Dothiorella spp.), which was likely due to the increased DTR in these treatments. Significant differences in disease severity were found between orchards (replications), with replicates with low disease severity being less affected by 1-MCP treatment. These results indicate that 1-MCP can delay ripening, but careful sourcing of fruit is required to reduce the risk of diseases in ripe fruit. There is some capacity to delay ripening using 1-MCP after ethylene. There is little potential to control ripening using ethylene after treatment with 500 nL L-1 1-1-MCP, but lower concentrations may be more effective. (C) 2004 Elsevier B.V. All rights reserved.